Superposition data transmission for cognitive radios: Performance and algorithms

Abstract

For improvement of achievable rate region in cognitive radio channels, a transmission method for secondary users is proposed. At first, the rate region of the sensing based cognitive radio scheme in which secondary users access the channel based on their channel sensing results with sensing error is analyzed. In the multi-user information theory, it is well-known that interference channel cases where both users transmit their own signal simultaneously achieve better rate region than the time-sharing method based on sensing outcomes. Based on this theoretical result, we propose the new transmission scheme in which a secondary transmitter relays primary user's signal with a full-duplex amplify and forward (AF) manner while transmitting its own data at the same time. In the proposed method, we take account of practical implementation issues which are ignored in the theoretical method guaranteeing an upper bound of a rate region. With different geometric locations and power ratios between the relaying signal and the secondary user's one, we evaluate the achievable rate region of the proposed method and compare with those of the conventional ones.

Full-Duplex Cooperative Cognitive Radio with Transmit Imperfections

“…However, DPC requires noncausal information about the primary message at the CBS, in addition to its implementation complexity; therefore in practice, it is unknown how to achieve this region. FD for CR is first proposed in [20] where the CBS uses AF protocol and superposition at the CU to improve the rate region. However, [20] assumed that at the CBS, the separation between the transmit and receive antennas is perfect and there is no selfinterference, therefore it only provides a performance upper bound for the FD.…”

Secure Spectrum-Sharing Wiretap Networks With Full-Duplex Relaying

“…Different from traditional cooperative jamming scheme that relies on cooperative jamming node mobility, trustworthiness and synchronization, FD jamming scheme is much easier and more reliable to realize. In [19], the FD technique was first proposed with the idea that the FD operation was employed for enhancing the secure transmission. In [20], the authors analyzed the SOP of the FD receiver, the cooperative jamming strategies with different relay selections and the sophisticated power control for enhancing the secrecy performance.…”

Optimal channel sensing maximising sum rate in cognitive radio with multiple secondary links

“…To the end, the frequency band, which is allocated to the primary network, is shared with a secondary network if the interference from the secondary network does not cause harmful effects on the primary operation. Several approaches have been proposed in . To avoid the interference to the primary networks, the secondary users can access the shared channel if it senses that the channel is idle.…”

“…The spatial opportunity can be exploited when the secondary users have the channel state information between a secondary transmitter and a primary receiver . The secondary user can act as a relay that transmits the received signal from a primary transmitter and its own signal as in . With this approach, the capacity of cognitive radio channels can be analysed.…”